Conventionally, a cleaning operation using a cleaning solvent is carried out during manufacturing electronic equipment, precision machines, and the like to prevent degradation of electrical characteristics and mechanical characteristics. Chemically stable chlorine or flon solvents have been used for this purpose. The use of a number of these solvents has been regulated due to the problems in safety, toxicity, and environmental pollution.
Cleaning solvents and cleaning compositions that are safe, less toxic, and less pollutant to the environment have been proposed as substitutes for these solvents. For example, cleaning solvents and cleaning compositions described in U.S. Pat. Nos. 4,511,488, 4,640,719, 4,740,247, JP-A 3-62897, JP-A 6-49495, and the like are given.
However, these cleaning solvents are not necessarily satisfactory in their detergency, particularly detergency for oils and fats. Therefore, development of a novel cleaning solvent excelling in both safety and detergency has been desired.
Conventionally, ether solvents that are non-protonic and polar have widely been used as reaction solvents for various organic reactions (hereinafter referred to as “reaction”) such as a Grignard reaction. Tetrahydrofuran (THF), which is a typical ether solvent, is a non-protonic and polar solvent having a moderate boiling point. THF is commonly used as a reaction solvent, particularly for Grignard reactions, reactions using an organolithium compound or the like, and other similar reactions. However, if THF is used as a solvent for a reaction mixture to which water is added, it is difficult to remove THF from the reaction mixture since THF is mutually soluble with water and forms an azeotrope. A special distillation process involving addition of an entrainer or other third components is required for industrially separating one component from another in an azeotrope. The distillation unit, which must be equipped with at least two columns and auxiliary equipment such as a decanter, can be operated only with difficulty requiring a high cost.
When THF is used as a reaction solvent for Grignard reaction in which a Grignard reagent such as phenyl magnesium bromide (PhMgBr) is reacted with a ketone that can be easily enolated such as acetone, a self-aldol condensation reaction which is a side reaction is predominant over the target nucleophilic reaction, producing the target reaction product (α,α-dimethylbenzyl alcohol) only in a low yield. Therefore, development of a reaction solvent that can be easily recovered after use and exhibits excellent reaction selectivity has been desired.
A solvent extraction is a well-known method for extracting a desired compound from a mixture using an appropriate extraction solvent. Various extraction solvents that can be used are known. Examples include halogenated hydrocarbons such as dichloromethane and chloroform; aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as benzene and toluene; esters such as methyl acetate and ethyl acetate; ketones such as acetone and cyclohexanone; and ethers such as diethyl ether and dipropyl ether.
Requirements for the extraction solvents include (i) being inactive under the extraction conditions, (ii) being capable of sufficiently dissolving extracted substances, (iii) having an appropriate boiling point, producing vapor that has a minimal risk of being absorbed during the solvent extraction operation, and being easily evaporated, and (iv) having only a slight possibility of polluting the environment.
However, only a few extraction solvents currently available satisfy these requirements. For example, since halogenated hydrocarbons such as dichloromethane and chloroform having excellent capability of dissolving various organic compounds have a strong toxicity and a low boiling point, their vapor have a risk of being inhaled during the extraction operation and cause an environmental pollution problem. Esters such as ethyl acetate and aromatic hydrocarbons such as toluene are also extraction solvents with wide versatility, but exhibit only limited capability of dissolving organic compounds having a moderate polarity and insufficient extraction efficiency. Therefore, development of a novel extraction solvent advantageous from the viewpoint of extraction operation and environmental safety has been desired.
Conventionally, various organic solvents such as aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, and halogenated hydrocarbon solvents have been used as a solvent and parting agents for electronic materials, electrical materials, and the like. It is desirable that these solvents and parting agents exhibit high solubility and dispersibility of electronic and electrical materials and are safe and free from the problem of environmental pollution.
However, not a few currently available solvents and parting agents lack solubility and dispersibility of electronic and electrical materials, are strongly toxic, and pollute the environment. Therefore, development of a solvent and parting agent exhibiting high solubility and dispersibility of electronic and electrical materials and being safe and free from the problem of environmental pollution has been desired.
As the method for producing ethers by the addition reaction of an olefin to an alcohol, a method of using crystalline alumino silicate as a catalyst (Japanese Patent Application Laid-open No. 59-25345), a method of using HZSM-5 zeolite as a catalyst U.S. Pat. No. 4,306,100), a method of using special alumino silicate having many acid points on the surface as a catalyst (Japanese Patent Application Laid-open No. 61-249945), a method of using tungsten oxide in which the crystal water possessed by a heteropoly acid has been adjusted to about 3.0 or less molecules per one molecules of the heteropolyacid as a catalyst (Japanese Patent Application Laid-open No. 5-163188), and the like are known.
However, the activity of the catalysts used in these methods has been insufficient to manufacture the target compound at an industrially acceptable selectivity and conversion rate, particularly to manufacture a cycloalkyl alkyl ether compound from an alicyclic olefin as a starting raw material.
A method of using an acidic ion-exchange resin is an old method for producing ethers by the addition reaction of an olefin to an alcohol. However, the method involves problems such as isomerization of olefins as a side reaction and thermal instability of used resins if conventional acidic ion-exchange resins are used as described in Japanese Patent Application Laid-open No. 5-163188, for example.
The present invention has been achieved in view of this situation. A first object of the present invention is therefore to provide (a) a novel cleaning solvent that can be safely handled, can be mixed with many organic solvents and dissolve various pollutant organic substances such as fats and oils, waxes, and natural resins, and can be promptly decomposed in the atmosphere without adversely affecting the ozone layer, (b) a reaction solvent that can be easily recovered after use and exhibits excellent reaction selectivity, (c) an extraction solvent advantageous from the viewpoint of operational efficiency and environmental safety, (d) a solvent for electronic and electrical materials exhibiting high solubility and dispersibility of the materials and being safe and free from the problem of environmental pollution, and (e) a solvent usable as a parting agent used for removing a photo-sensitive layer from an OPC (Organic Photo Conductor) drum or for removing semiconductor materials and the like glued to jigs with an adhesive from the adhesive or the jig.
A second object of the present invention is to provide an industrially advantageous process for producing a cycloalkyl alkyl ether compound useful as such a cleaning solvent, reaction solvent, extraction solvent, parting agent for electronic or electrical materials.